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A.~.7 Commercial Communication Services Commercial services have ITS applications and win be increasingly Important as Advanced Traveler Formation Systems (ATIS) are deployed. Historically, implementation/operation of Advanced Traffic Management Systems (ATMS) has not found commercial infrastructure to be cost competitive wad private networks, as indicated in He survey conducted as a part of Phase of this project. This section win address: Rates for Commercial Services Satellite Communications Broadcast SubcalTiers for ITS Commercial Wireless Services, and ISDN. A.~.7.1 Rates for Commercial Services Rates for commercial services vary widely by geographic area and service provider. This section win briefly summarize rates that have some consistency nationwide. Table A.~.7.! presents representative cellular rates. Depending on preferences, users may select monthly access rates, peak/off-peak, and nightly rates; including free minutes in the monthly access rate; and/or including a service contract. Table A.~.7.~-2 presents wireless data service rates. Emerging CDPD services win influence these rates in He future. Table A.~.7.~-3 presents ISDN rates. L:\NCHRP\Phasc2.rpr\ NCHRP3-51 Phase2F~nalReport A1-255

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Table A.~.7.1 Representative Cellular Rates | Average Monthly Access | $30 - $189 per month | Peak per/minute . | $.25 - $.60 per minute | Off-peak per/minute | $.05 - $.030 per minute Night $0 - $.30 per minute Included free minutes ~ Peak 0 - t200 Night 0 - 200 Offpeak 30 - 100 Service contract (years) 1 - 3 years . ~ Peak: 7:00 am - 8:00 pm, Monday - Fnday Offpeak: 8:00 pm - ~ ~ :00 pm, Monday - Fnday 7:00 am - Il:OO pm, Weekends Night: Il:00 pm - 7:00 am, 7 days Table A.~.7.~-2 Wireless Data Service Rates Monthly Rate $ | kilobytes | , _ ARDIS $19.95 20 _ $50.00 150 $100.00 350 $190.00 750 _ RAM $25 100 $65 200 $88 275 _ $135 500 CDPD _ Amentech $20 100 $55 500 $99 1,000 AT&T $15 50 $50 500 $ each additional kilobyte $.54 $.35 $.33 $.31 $.27 $.20 $.11 $.10 $.11 to$.16 $.08 L:WCHRP\Phase2~pt\ NCHRP3-51 Phase2FmalReport A1-256

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Table A.~.7.~3 tSDN Rates Monthly Access Rate ~ Per Minute Basic Rate Circuit (BRI) $19 - $90/month $.00 - $.15/minute 2B ~ D = 2 x 64 + 16 = 144 (Typically standard ~WP) kbps Primary Rate Circuit ~ $1,000/month Nl/A 23B ~ D = 1.544 Mbps (Requires 2 TWP) ISDN circuits have various combinations of B (bearers channels and D (data) channels. Normally, one D channel is provided for network control/monitoring/connection functions; however, the B channels can be configured as individual voice channels or consolidated for higher speed data access. Often these special configurations require telephone company configuration support, and perhaps additional charges. The traffic on T} and SONET/fiber circuits varies Widely. For this reason, we have not included pricing data. Local service providers can provide pricing information. With passage of the 1996 Telecommunications Act, a competitive environment may soon emerge, drastically changing services, provider options, and prices. (This space intentionally left bland) ~wCHR~.rpt\ NCHRP 3-51 Phase 2 Fmal Report A1-257

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A.~.7.2 Satellite Communications by Comsat Laboratones CIarksburg, Maryland A. 1.7.2. 1 Satellite Alternatives and ITS Applications There are many areas in which satellite communications can be applied to ITS, often providing the best solution to a problem. The applications can be categorized into several areas. Table A.~.7.2.~-1 presents five broad applications of satellite communications, with specific examples of each. A.~.7.2.2 SafeIIife Performance Charaeferisfics This section covers We venous aspects of a satellite system and Weir effects on We overall performance character~shcs. Initially, the key features of sateHite-based communications are presented. Then, a discussion is offered on We ~eory/concepts of satellites as a communication medium. This is followed by short explanations of We various aspects of a satellite system such ., as orbits, satellite frequencies, channel bawds, typical digital bit-rates, and coverage capabilities. Key features of satellite-based communications There are many unique advantages to using sateDite-based communications. The key features of sateUite-based communications (as compared to terrestrial commurucabons mediums) are presenter! In Table A.~.7.2.2.~-~. L\NCHRP\Phase2.rpt\ NCHRP3-51 ~ Phase2FinalReport A1-258

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Table A.~.7.2.~-1 Applications of Satellite Communications to ITS 1 2 Applications Broadcast Information (Could be transmitted to specific regions or broadcast nationally.) Data collection (Sensors could be rapidly deployed to areas of concern or interest without reworking a ground network.) 3 Transmission of control information (To specific sites or groups of sites.) Examples Comments . _ . Highway Advisory Including delivery of: Traffic flow Radio data, road conditions, detour information, other public service information Transmission of Including delivery of: Weather weather-related data forecasts and current road conditions (raintsnow storms, icy roads, high winds, low visibility, and other weather-related phenomena which impedes traffic) Traffic-related video Including delivery of: Detour maps' information hazardous-area maps, traffic congestion (video/maps), and other visual information _ Traffic flow-rate Report traffic flow information for sensors critical sections of highways (congested areas, construction zones, etc.) . _ Weather-related Indicate when roads are freezing, sensors flooded' experiencing high-winds, or low-visibility Highway Issue regular reports on the status superstructure stress of bridges, tunnels, overpasses, monitoring sensors and other vulnerable structures Smart signs Notify travelers of traffic congestion and suggest alternate routes Traffic flow control Include changing traffic light timing devices or controlling various traffic control-gates, based on traffic flow data National roadside Dropped off and set-up within assistance phones minutes Collision activated Transmit distress beacon to a distress beacons national reaction center along with precise location of vehicle Highway officials and Broad range of transmission rates' law enforcement from low (modem-type) data to personnel voice transmissions, up to a full T1-rate for backbone data services 4 Emergency/distress . communlca. :lons services 5 Two-way voice/data - communications L:\NCHRP\Phase2.rpt\ NC~P3-51 Phase2FmalReport A1-259 I

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Theory/concepts of satellites as a communication medium In general, a satellite may be considered to be a distant radio-freguency ~F) communications repeater that receives upland transmissions and re-transm~ts them in its downlink beams. Figure A.~.7.2.2.2-! illustrates the end-to-end communications required in establishing a satellite link. The link is shown in its most generic form with transmit and receive capabilities at both ends. Such facilities are characteristic of the two-way fixed and mobile services. Broadcast and data collection applications transmit only at one end and receive only at Me over end of We lick. The overall problem can be divided into two parts. The first deals with the satellite RF link which establishes communications between a transmitter and a receiver using the satellite as a repeater. In describing the satellite radio link, we quantify its capability in terms of the overaU available ca~Tier-to-noise ratio (C/N)A. This figure of merit, representing the ratio of the carrier power (the desired signal) to the noise power measured in a bandwidth, is directly related to the channel-carrying capability of Me satellite linlc. The value of (C/N)A depends on a variety of factors, which in turn depend on the available power and bandwidth for the earner. The second part of the problem concentrates on Me link between the earth terminal and Me user environment which, in most small systems, is incorporated into the user equipment. In the user environment customers are typically concerned with establishing voice, data, or video communications with either one-way or two-way connections. The quality of these ~`baseband', links is characterized by venous figures of merit such as transmission rates, error rate, signal-to- noise ratio, and other performance measures. For example, a data communications link used to transmit financial account balances must exhibit an extremely low rate of error to be effective. The error-rate specification for such a data communications service is directly translated into a required rate (C/N)Req per channel. The two parts of the problem can then be finked together when Me available (CIN)A of Me satellite link is compared to the required (C/N)Req dictated by the user application. The difference between the required (C/N)Req and the available (CIN)A is called Me link margin. Usually a link is designed to achieve a certain link margin, which is used as a buffer against occasional link degradations which are largely weaker related. The selection of ail appropriate link margin is highly dependent upon Me link's operating environment and its availability requirements. Availability is the percentage of Me time Mat Me link must operate LO\ NC~P 3-S! . Phi 2 Fin Report A1-261

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without a serv~ce-outage (typical availabilities range from 95% to better than 99.9% of the year). Intelsat fixed service offers an availability of 99.96%, unless redundant sites are used. The Satellite RF Link Ihe performance of a satellite link is typically specified in teens of its channel capacity. For this discussion, the following definitions are relevant. A channel is a one-way link from a transmuting earth station through the satellite to Me receiving earn station. A circuit is compnsed of two channels used for bi-dimctional communications between two earn stations. The capacity of a link is specified by We types and numbers of channels and the performance requirements of each channel. In practical terms, a voice service must provide circuits to its customers. The term "channel," however, may also apply to television and data circuits as well. For broadcast and data collection applications, one-way channels are typical. The channel-caIIying capacity of a satellite RF link is directly related to the overall available carner-to-noise ratio (C/N)A . Exclusive of interference, three basic elements are considered in designing this RF lick. The first is the uplink, representing the channel from Me transmitting earth station to Me satellite. The quality of this link is usually expressed in teens of Me uplink carrier-to-noise ratio (CINJu . The (C/N)U depends on the power of the transmitting each station, the gain of Me transmitting antenna, the gain of the receiving antenna, and Me satellite system noise temperature. The power of the transmitter on the ground depends on the size of the power amplifier employed. The gains of both the transmuting and receiving antennae are directly related to Heir sizes and efficiencies. The system noise temperature is a measure of Me degradation of the received signal caused by elements in Me receiver. This is composed of the receiver's amplifier noise the noise due to losses between Me antenna and Me amplifier, and Me antenna noise. \NCH]WhaS~\ NCHRP3-51 PhaSe2Fina1RePOrt A1-263

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The second element In Me RF link is the downlink. The corresponding figure of merit is caned the downlink caIrier-to-noise ratio (CM)D . Similar to We uplink, (C/N)D depends on Me power of the satellite transmitter, the gain of Me transmuting and receiving antennae, and Me earn station's system noise temperature. The third element to be considered in Me RF link design is Me satellite electronics system itself, which produces undesirable noise-like signals Mat are normally expressed in a caner-to-noise ratio which we can cad (~/N)I . Sever impairments, pnmarily intetmodulation effects caused by the non-linear operation of the satellite amplifiers, can be included In the (CHILI component. Interference from over satellites and terrestrial systems can also be coBec~vely characterized by a carner-to-~nterference ratio. one makes certain typical assumptions about He nature of Me noise-~ce impairments, then the three elements [(C/N)U (C/N)D and (CIN)I ~ can be easily combined to yield an overall camer- to-noise redo, (C/N)A . Due to the way this overall available camer-to-noise ratio (C/N)A is calculated, it can never be better Man Me worst of the three individual elements. Two basic components are required to establish a satellite link. The first is the satellite repeater, usually carded a transponder, and the second is a satellite earn station. The Satellite Transponder A satellite functions as a distant RF communications repeater which receives uplindc transmissions and provides fiItenug, amplification, processing, and frequency translation to the downlink band for retransmission. These sub-functions are briefly descnbed below. The typical transponder is a quasi-linear repeater amplifier, a block diagram of which is shown Figure A.~.7.2.2.2-2. The uplink and downlink bands are separated In frequency to permit simultaneous transmission and reception without self-interference. Moreover, Me lower- frequency band is normally used on the downJink to exploit the reduced atmospheric losses (at these lower frequencies), thereby minimizing satellite power amplifier requirements. Typical satellite transponder amplifiers must provide relatively large gains (amplifying Me signal power from 100 million to 10 billion times) while maintaining relatively low-noise operation. Channeliz~ng filters must be designed to minimize interference from adjacent channels, as well as [.WC~.~.Q,lK NCHRP3-51 ~ Ph~2~RePOrt A1-264

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Use of Time Division Multiple Access (TDMA) digital modulation which permits multiple ~ . users on one frequency pair. Use of Code Division Multiple Access (CDMA) which permits multiple users on one frequency pair. CDMA is a form of spread spectrum digital modulation (see Section A.1.3.4). Competing standards have emerged in bow the cellular and PCS services. Both TDMA and CDMA are digital modulation techniques and requure speech codecs that digitize and compress the analog speech signal. The quality of the speech codec Algonquins is a significant determinant of die user's perceived quality of service. These digital modulation techniques, when widely deployed, can efficiency support data without a modem. None of these competing digital standards have substantial current U.S. deployment in either cellular or PCS. AMPS is still dominant; however, PCS win be deployed more as competitive pressures win undoubtedly force an eventual transition to digital cellular for added capacity and additional features. Table A.~.7.4-2 presents He primary cellular/PCS systems in Be U.S. and key operational parameters. It should be noted that Global Systems for Mobile (GSM) is an adaption of Be European system for emerging PCS services and has been selected by several PCS service providers because equipment is available for rapid deployments. CDMA has been selected by several of Be service providers because it debatably offers increased capacity. Unlike analog cellular, digital cellular and PCS have multiple deployed standards. Time and the marketplace will determine user acceptance. Cellular Digital Packet Data (CDPD) is a service available from analog cellular providers, which offers packet data capability in the cellular bands. CDPD Besets bursty packet data on idle cellular analog channels. Because it fits data between voice conversations, CDPD has not yet (early '96) verified that it will operate satisfactorily in overloaded metropolitan areas. S~m~lar CDPD services will be offered via digital cellular/PCS bands and the already digital modulation may provide more cost effective services and equipment. The PCS bands are being auctioned and few are operational in '95/'96. The allocated frequency bands are presented in Figure A.~.7.4-2. It should be noted Mat Be FCC has allocated bow t.:`NC~Phasc:.rpr\ NCHRP3-51 Phase2FinalReport A1-326

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licensed and unlicensed bands. As previously noted, PCS will be digital on initial deployments. It should also be noted that the FCC PCS frequency avocations constrain two unlicensed bands. One is asychronous for packet data applications and one is isochronous (equal delay) for potential voice/video applications; such as wireless PBXs. Two wireless packet data services offer commercial capabilities using He Specialized Mobile Radio (SMR) frequencies near 800/900 MHz, offering coverage to about 90% of urban business areas. Advanced Radio Data Infotmabon Service (ARDIS) is available in more than 200 metropolitan areas. RAM Mobile Data (RAM or RMD) service is available In 216 metropolitan areas. ARDIS and RAM have more Han 52,000 subscribers nationwide. Table A.~.7.4-3 provides an overnew of these services and, for comparison, equivalent information on CDPD. Table A.~.7.4~3 Commercial Wireless Data Services ARDIS ~ RAM ~ CDPD Mobitex Architecture) Data Rate | 4.8 kbps | kbps | 19.2 kbps 19.2 kbps Frequency Band | SMR | MR | Cellular l 800/900 MHz 800/900 MHz 824 - 894 Mbps Number of Channels 10 - 30 Cellular frequencies each Metropolitan area Coverage ~410 MSA 210 MSA 50 MSA (MSA- Metropolitan Service Area) Comment ~ Proprietary protocol ~ Proprietary protocol ~ Public protocol Analog modems over c~rcuit-sw~tched celdular phones are frequently used for wireless data transmissions. These are typically the V.32/V.34 wireline modems; however, He cellular telephone network has different characteristics from He standard wired network and special protocols are required for reliable commun~cabon. Two ceDular-specific error correction protocol standards are employed: 1) Enhanced Throughput Cellular (ETC), developed by AT&T (now Lucent Technologies); and L;`NCH~Phase2.~p~\ NCHRP3-51 Phase2FinalReport A1-330

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2) Microcom Network Protocol lO Enhanced Cellular (MNPlOEC), developed by Rockwell International. Both of these protocols are extensions of the ITU V.42 error control and correction protocol. It should be noted that, even with special cellular protocols, He throughput (byte per second) can be substantially less Can rated land line circuit performance. In addidon to the proliferation of wireless communications services, the wireless explosion is providing many standard "air interfaces" Mat could prove useful and adaptable to ITS applications. A.1.7.5 ISDN Integrated Services Digital Network (ISDN) is a digital dialup telephone service that was conceived to provide end-to-end digital telephone service. After years of hype and unrealized potential, ISDN appears to have achieved some recent successes largely as a result of demand for higher speed (compared to dialup modem) access to Internet services. It is also widely used by the radio broadcast industry for higher quality voice transmission from remote sites (e.g., sports arena, etc.) and win offer similar benefits to rRs. For years, He commercial telephone network has employed digital switching, multiplexing (i.e., T! digital hierarchy), and transmission. However, the TWP connecting He Central Office (CO) switch to subscriber telephones has been analog as depicted in the lower part of Figure A.~.7.5-! ISDN essentially extends the digital DS-O (or B channel In ISDN terminology) to He subscriber premise as depicted In He upper part of Figure A.~.7.5-~. A D (or data) channel is also provided to serve the equivalent telephone signallcontro] fimctions such as on/off hook, DTMF dial tones, busy signal, etc., tones Hat are provided "in-band" on He standard analog telephone circuits. Additionally, this D channel may also serve as a packet data channel for packet services, although most current services appear to use B channels. L;mC~Phasc2~p~\ NCHRP3-51 Phase2FmalReport A1-331

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ISDN is basically a WAN service that is available In two forms: Basic Rate Interface (BRI). Primary Rate Interface (PRO. BR] provides the following: 2 B Channels (DS-O, 64 kbps) for a total of 128 kbps. ~ D Channel at 16 kbps. Deployment over existing telephone company TWP loop plant by providing ISDN terminals at bow the customer premises and Be service CO (also in Figure A.~.7.5-~. PRI provides: Essentially DS-] service at 1.544 Mbps Up to 23 DS-O channels available within the DS-l frame, (although over rates can be supported). ~ D channel at Be DS-O rate of 64 kbps. This requires special 4-wire TWP circuits and repeaters for longer distances (the equivalent of T1 DS-1 circuit requirements). N L:\NCHRP\Phase2.rptN NC~3-51 ~ P~2F~Re ~A1-333

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Endnotes: 1. The infrastructure can be a regional traffic center, an incident center, a real-time map update facility, etc. 2. The Communications Act of 1934 (as amended) requires He FCC to judge all requests for radio spectrum by determining if the need is "in the public interest, convenience or necessity." 3. SCA, or Subsidialy Communications Authorization was a FCC description that was deleted from the FCC Rules (47 CI;R 73) in a rule making proceeding in 1983. It was replaced by the description Subsidiary Communications Service, but the initials SCS never caught on. In any case, these terms are very narrow and exclude F'M RDS and various TV aural subchannels. In addition, neither SCA nor SCS are descriptive of the channels. Calling these channels "broadcast subcamers" is both inclusive and technically descriptive. 4. Edwin H. Armstrong, "A Method of Reducing Disturbances in Radio Signaling by a System of Frequency Modulation," Proc. of the I.R.E., Vol 24, No. 5, May 1936. Repunted; Jacob Klapper ed, Selected Papers on Frequency Modulation, Dover, New York, 1970. 5. A minor exception to this is in the case of non-commercial FM stations that must, if they use any subcarriers for profit making activities, make an additional one available for use by radio reading services for the blind. 6. Effective radiated power is the transmitter power output available at the antenna multiplied by the gain of the antenna 7. This is a holdover from ten years ago when there were FCC Rules governing subcarrier technical operations. Today there are no such rules, but the practices continue from 'Force of habit." 8. There is a large distinction between "throughput" or the information rate and the signaling speed. Depending on Me level of error correction, the signaling speed may be several times faster Wan the data throughput. The later section "Data Rates" discusses this issue in more detail. 9. T. Beale and D. Kopitz, " RDS in Europe, REDS in Me USA ~ What are Me differences and how can receivers cope win bow systems?," European Broadcasting Union (EBU) Renew - Technical, Spring 1993, pages ~8. 10. "United States REDS Standard, Draft No. 2.0, NRSC Document, August 1, 1992" National Association of Broadcasters and The Electronic Industry Association. 11. A. G. Lyner, '~xpenmental Radio Data System (RDS): A Survey of Reception Reliability in the UK," Report BBC RD 1987/17, British Broadcasting Corporation Research Department, Engineering Division, Nov 1987. 12. Ibid. 13. "IKE Colloquium on 'The RDS System - Its Implementation and Use' (Digest 128)"; IKE, London, UK; Dec 1988. 14. K. H. Schwaiger and J. Mielke, 'prowess With He RDS System and Experimental Results," European Broadcasting Union (EBU) Review - Technical, No. 217, June 1986, pages 150~158. 15. F. Stollenwerk and N. Pfeiffer, 'first Operational Results of the Radio Data System (RDS)," lIG-Fachberichte, Vol 106, Pages 123-128, 1988 (In German). L.\NCHRP\Phasc2.'ptY CHAP 3-51 Phase 2 Fmal Report A1-334

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16. J. H. Paffenbarger, "Optimized Implementation of SCA Subcarriers for Minimum Degradation of FM Stereo Reception," Proceedings: 41st Annual Broadcast Engineenng Conference; 1987, National Association of Broadcasters, Washington, DC. A contrary position is taken by Paffenbarger. However, the FM station discussed is a fine arts type of station much closer to the traditional European norm than the U.S. 17. This may be a self seeing position for some non-commercial fine arts stations. Non-commercial FM stations are obligated by the FCC to provide subcanier service to reading services for the blind if they make commercial use of any of their subca~riers. Objecting to subca~Tiers on technical grounds offers an credible way to refuse being forced to "give away" one of their subcarriers. 18. Ibe character of broadcasting, especially FM, is changing in Europe win He Mowing movement toward private ownership of radio and television stations. These new stations are evolving very much in He style of U S. commercial broadcasting. 19. D. J. Thyme, 'the transmission of Two Program~s From Band ITEM Transmitters: an assessment of 'Storecasdng'," Report BBC RD 1976ll4, British Broadcasting Corporation Research Department, Engineenng Division, June 1976. Reprinted in the European Broadcasting Union (EBU) Review - Technical, No 161, February 1977, pages 20-30. 20. In the presence of competing signals, as is the case in the FM band, the greater the average deviation (loudness), the greater and more reliable will be the coverage of the radio station. 21. The visual portion of He TV signal is much more susceptible to interference from other visual signals, so it sets the spacing requirements between stations. The aural carrier is significantly more resistant to interference than the visual, so it gets a "Bee rice" in terms of interference Tom other aural signals on the same channel. In addition, because the TV sound channel is adjacent in frequency to Be much wider band visual signal, interference from stations on adjacent channels is not an issue. This contrasts wig FM stations, for which adjacent and co-channel interference is the major factor in limiting coverage. 22. "OET Bulletin No. 60, Revision A"; Office of Engineering and Technology, Authorization and Evaluation Division; February 1986; Federal Communications Commission. 23. The frequency response is 50 Hz to 101tHz, with a signal-to-noise ratio better Han 60 dB. 24. The FCC Rules - 47 CORK 73.682(c)~1-9) provide Hat a television station may use non program related subca~riers from 16 kHz to 120 1~z at a total deviation not to exceed 50 kHi. 25. Data WorId or ITS Boulder, div of NIST. 26. The Federal Communications Bar Association, 1150 Connecticut Avenue N.W., Swte 1050, Washington, DC 20036. Telephone (202) 833-2684, fax (202) 833-1308. L;\NC~.rPtN NCHRP3-51 Ph~2F~RePOrE A1-335

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